Substance P belongs to a family of bioactive neuropeptides known as the tachykinins. Payan (1989) Ann. Rev. Med. 40:341. It is believed to be involved in the neurotransmission of pain sensation as well as a host of other biological functions.
Chronic exposure to jet fuel, common among refueling crews and aircraft mechanics, causes a wide variety of symptoms. Workers in a jet motor factory, for example, reported headaches, dizziness, and "thoracic oppression" (Struwe et al., Acta Psychiat. Scand. 303(S):55-67 (1983); Dossing et al., Scand. J. Work Environ. Health 11:433-437(1985)). Inhaled and absorbed hydrocarbons or their metabolites may act on the central nervous system to produce neurasthenic syndrome in subjects exposed to jet fuel (Struwe et al, 1983, supra). Jet fuel may also have toxic effect on the liver, kidneys, and pulmonary system (Struwe et al., 1983 supra; Gaworski, et al., (1984) in: Advances in Modern Environmental Toxicology, Vol. VI, Applied Toxicology of Petroleum Hydrocarbons (H. N. MacFarland, C. E. Holdsworth, J. A. MacGregor, R. W. Call, and M. L. Kane, eds.), Princeton Scientific Publishers, Princeton, N.J. pp. 33-47; Dossing et al., 1985, supra; Witten et al., (1990), Substance P and Related Peptides: Cellular and Molecular Physiology International Symposium, University of Massachusetts Press and the New York Academy of Science, p. 29.; Mattie et al., Toxicol. Pathol. 19(2):77-87 (1991)). Occupational exposure to jet fuel causes mucous membrane irritation, enhancing the clearance of antipyrine. The antipyrine test assesses microsomal enzyme activity, which can be altered by organic solvents (Dossing et al., 1985, supra).
JP-8 jet fuel is a kerosene type fuel which has become the United States military's main fuel source for aircraft as well as other types of military equipment. However, as discussed above, there are indications that jet fuel inflicts damage on those who must work with it.
Exposure to environmental toxicants may have significant effects on host systems beyond those readily visible (e.g., physiology, cardiology, respiratory, etc.) Such exposure may have profound and detrimental effects on the immune system that result in significant host impairment in terms of immune competence, susceptibility to infections, and future development of neoplasms.
Depending on the type of environmental toxicant and the route of exposure, the damage to the immune system may be minor and inconsequential, or it may be deleterious with long-lasting effects. Significant changes in immune competence, even if short-lived, may have serious consequences for the exposed host in terms of lymphopenia that may impinge upon susceptibility to infectious agents. Major alterations in immune function that are long-lasting may result in increased likelihood of development of cancer and autoimmune disease.
Viral infections, such as HIV, can also impinge upon the welfare of a person's immune system. In addition, the status of the immune system can affect a person's susceptibility to infections. Thus, there is a continuing need in the art for methods of counteracting the effects of toxic insults such as hydrocarbons to the body, especially those which affect the immune system.